The invention relates to a tubular bagging machine comprising a foil web, a storage roller, guide rollers for feeding the flat foil web to an asymmetrical forming shoulder, whereby the front collar parts of the forming shoulder have different lengths, a foil removing means to transport the foil web, a fill pipe to receive the foil web, which has been shaped into a foil tube, jaws of a transverse welding device for creating cross-seams, a separating device for separating the foil tube, and flat expanding elements connected to the fill pipe and extending away from the fill pipe, whereby an edge-welding device is provided for each expanding element in a foil transport direction arranged downstream of the expanding elements, each edge-welding device being directed against the edge of the tube deflected by each respective expanding element.
Such a known tubular bagging machine is used to manufacture tubular bags, the four edges of which are welded. These tubular bags have a relatively good stability. By using the asymmetrical forming shoulder the longitudinal seam, which otherwise extends centrally with respect to the bag, is offset to one edge of the bag so that a separate longitudinal seam no longer exists.
In another known tubular bagging machine a longitudinal seam, which is arranged centrally with respect to the bag, is created by means of a symmetrical forming shoulder. The edges of the bag are separately welded so that a bag has five longitudinally extending welding seams.
Whereas a bag with merely four longitudinally extending welding seams does not have a longitudinal seam, which interferes with the printing on the bag, a common, symmetrical forming shoulder can be used for the manufacture of a bag with a central longitudinal seam.
The known tubular bagging machines do not offer the possibility of manufacturing bags with opening aids or reclosing aids, which are easy to handle, so that this aid utilizes the special shape of the bag welded along its four edges.
The basic purpose of the invention is to overcome these disadvantages.
The purpose is attained by providing a separate longitudinal welding device for a welding of the area adjacent to the edge of the tube.
The invention has the advantage that because of the two welding devices, which are provided at one edge of the tube, namely an edge-welding device and the separate longitudinal welding device, two longitudinal seams are created directly side-by-side in the area of the tubular edge, where the foil tube is being longitudinally closed. One of these two longitudinal seams can be a seam which is relatively easy to open and cannot be closed again, and the other seam can be used as a seam which can be easily opened or again closed. Or, however, one seam fulfills due to its edge welding first of all the purpose of stabilizing the bag and the other seam is used to securely close the bag. Then the seam, which, for example, welds the edges, has generally less strength than the longitudinal seam welding the bags.
A so created bag has special importance also when the outer seam, namely the seam to be opened first, is a seam to be opened in a simple manner, and the following seam fulfills the function of the edge stabilization. The seam to be opened first can hereby be equipped with a reclosing aid.
When the longitudinal welding device is shifted with respect to the edge-welding device, which is adjacent to it, toward the edge of the foil, then the longitudinal welding device causes the closure of the foil tube at the point where the two edges of the foil meet. An edge area follows these edges. This arrangement permits in a simple manner the creation of bags welded at four edges with a longitudinal seam defined by one edge. The edge can hereby also be designed without a bag-closing characteristic.
The suggested tubular bagging machine is used for both the manufacture of bags, the edge of the foil of which extends away from the bag (foil tube) in the form of a fin, and also for bags, the edge of the foil of which rests on the bag (foil tube) in the form of an overlapping seam or a fin. The edge of the foil resting on the bag can be accomplished, for example, by means of a suitable welding.
The tubular bagging machine can be operated continuously or cyclically. The foil removing means is operated accordingly. Rotating endless bands and a rotating system of cross-jaws are suitable for a continuous longitudinal welding operation. Hot-sealing jaws, which are cyclically operated, can be utilized during a cycled operation.
Side-fold producers are used to create side folds in the foil tube. A pair of side-fold producers, which can be moved toward one another is utilized to create two opposing side folds in the foil tube. Thus tubular bags are welded with two opposing cross-seams each by means of two pairs of side-fold producers, whereby one pair is provided in foil transport direction in front of the transverse welding device and one pair downstream of the transverse welding device. These bags are very inherently stable. They are welded at the top and bottom by means of cross-seams. The side folds are welded into the cross-seams. When the distance of the one pair from the transverse welding device is equal to the distance of the other pair from the transverse welding device, then the bag is symmetrical with respect to its side-fold arrangement and can be shaped relatively round in order to have, when set on edge, a can-like appearance and to serve advantageously as a can replacement (material savings).
When the forming shoulder has a lateral slot, through which the edge of the foil is guided, then the tubular bagging machine can be equipped with a common, however, slotted, asymmetrical forming shoulder.
A preshaping of the edges can occur in a technically very simple manner independent of the type of operation of the tubular bagging machine when two foil hold-back means are provided in the area of the forming shoulder, which foil hold-back means are each arranged between two foil expanders in order to preshape the foil tube for a welding of the edges. These foil expanders are mounted on the fill pipe for an assured preshaping.
When a device for mounting of a bag-opening aid or a reclosing aid is mounted on the flat foil web, and when this aid is intended for introduction into the longitudinal seam and/or the edges to be welded, then a selected seam can be equipped with a suitable aid. As an aid is suited in particular (a) a strip-shaped peel layer in order to achieve an easy opening, (b) an adhesive strip with adhesive on both sides in order to achieve a secure lock in connection with a reclosing ability, and (c) an openable and recloseable structure in strip form in order to be able to achieve in particular repeated openings and closings of the bag.